Created attachment 115705[details]
Backtrace of crash
I managed to get a bt.
I first had to go to Debug - Event filters and disable Break instruction exception, because Windbg kept tripping over it immediately after attaching to LibreOffice.
Then I enabled Unknown exception in the filters.
Win 7 Pro 64-bit Version: 5.0.0.0.alpha1+
Build ID: 158b50763962f66515062300e265839828463efa
TinderBox: Win-x86@39, Branch:master, Time: 2015-05-19_00:28:31
Locale: fi-FI (fi_FI)

Created attachment 115731[details]
backtrace from the "throw"
If I have counted exceptions correctly, the backtrace is from the last
first chance exception before LibreOffice displays the error message.